JavaScript 浏览器验证代码(来自discuz)

var BROWSER = {}; 
var USERAGENT = navigator.userAgent.toLowerCase(); 
alert(USERAGENT); 
BROWSER.ie = window.ActiveXObject && USERAGENT.indexOf('msie') != -1 && USERAGENT.substr(USERAGENT.indexOf('msie') + 5, 3); 
BROWSER.firefox = document.getBoxObjectFor && USERAGENT.indexOf('firefox') != -1 && USERAGENT.substr(USERAGENT.indexOf('firefox') + 8, 3); 
BROWSER.chrome = window.MessageEvent && !document.getBoxObjectFor && USERAGENT.indexOf('chrome') != -1 && USERAGENT.substr(USERAGENT.indexOf('chrome') + 7, 10); 
BROWSER.opera = window.opera && opera.version(); 
BROWSER.safari = window.openDatabase && USERAGENT.indexOf('safari') != -1 && USERAGENT.substr(USERAGENT.indexOf('safari') + 7, 8); 
BROWSER.other = !BROWSER.ie && !BROWSER.firefox && !BROWSER.chrome && !BROWSER.opera && !BROWSER.safari; 
BROWSER.firefox = BROWSER.chrome ? 1 : BROWSER.firefox;